Republic: Book I Summary

Socrates and Glaucon are returning from a festival when they are accosted by a group of men who insist that they stay to see the later portion of the festival. Socrates agrees and the group goes to one of the men's house where Socrates meets and converses briefly with Cephalus, a rich, old man, about old age, which Cephalus says frees one from the passions of youth. The conversation then shifts to a discussion of the definition of justice, and Cephalus' place is taken by Polemarchus. Polemarchus proposes that justice is doing good to one's friends and evil to one's enemies. Socrates finds this definition insufficient, however, since doing evil to one's enemies would entail making them worse and, therefore, less just, but a just man could not produce an unjust man. Polemarchus concedes this point.

Thrasymachus, who apparently...